Nickel Foam Electrodes-A Versatile, Powerful, and Readily Available Tool in Electro-Organic Synthesis.

For more than 50 years, nickel foam electrodes have served in electrosynthesis as powerful and readily available electrode materials. Due to their inexpensive nature and easy handling, they have been widely employed. Their application as an active anode material, which generates a conductive and insoluble layer of NiOOH in alkaline media, gives access to a selective oxidizing system. While using NiOOH anodes as an electrocatalyst has already emerged in the past and was rediscovered lately, the use of nickel foam electrodes as a highly active cathode material for the reduction of organic compounds has strongly evolved only within the last decade. Electroreductions on nickel foam can be carried out in both alkaline and acidic media, as well as under protic and aprotic conditions, enabling a broad range of transformations. The affordability, high electrical conductivity, large electrode surface area, and specific electrocatalytic features are in combination unique and unmatched by any other electrode material. The developments and, in particular, recent breakthroughs for this electrode material in electro-organic synthesis are surveyed.